1. Field:
The present disclosure relates generally to aircraft structures and, in particular, to aircraft using composite structures. Still more particularly, the present disclosure relates to a method and apparatus for reducing noise in composite structures in an aircraft.
2. Background:
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. For example, some aircraft may have more than 50 percent of their primary structures made from composite materials. Further, composite materials also may be used in the interior of the aircraft and for other structures.
Composite materials are used in aircraft to decrease the weight of the aircraft. With the decreased weight, improved payload capacities and fuel efficiencies may occur. Further, composite materials also may provide a longer service life for various components in an aircraft.
Composite materials have a lighter weight and greater stiffness as compared to metallic structures. As a result, composite materials also are more efficient in radiating noise as compared to metallic materials. With the use of composite materials in place of metallic materials, noise in the interior of an aircraft may be greater than desired.
Currently, noise is controlled using different types of noise reduction systems. For example, dampening systems, fiberglass blankets, acoustic foam, isolators, and other systems may be used to reduce the noise generated by composite structures. These noise reduction systems, however, may be labor intensive for installation and may require additional space. Further, these types of systems also may be more expensive and add more weight than desired. Further, even with these noise reduction systems in place, the amount of noise reduction achieved may not be as great as desired.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above as well as possibly other issues.